The disclosures herein relate generally to annuloplasty rings and more particularly to an annuloplasty ring which is formed by two separable portions so that the entire ring or a separated portion of the ring is useable.
There are several commonly known forms of annuloplasty rings. As a result there are three general divisions within the technology for annuloplasty rings. These divisions are stiff vs. flexible rings, partial vs. complete rings and adjustable vs. non-adjustable rings.
A conventional ring, disclosed in U.S. Pat. No. 4,055,861, completely surround the mitral or tricuspid valve annulus with the intent of supporting the entire annulus to prevent dilatation of the natural tissue. U.S. Pat. No. 4,144,046 discloses an early use of a flexible, partial ring. Subsequently, U.S. Pat. No. 4,164,046 disclosed an incomplete or partial ring that reinforces the posterior portion of the mitral valve annulus but does not extend across the anterior portion of the annulus. It was believed by many that the fibrous anterior portion of the annulus is not subject to dilatation, in contrast to the muscular posterior portion of the annulus. Operative time can be reduced with the implantation of a partial ring because fewer sutures are required to secure the ring to the native valve annular tissue. Further, there is some risk of damaging the aortic valve leaflets when placing sutures in the anterior portion of the mitral valve annulus. A partial ring limits this concern. Some surgeons have now abandoned the use of a partial ring because in some cases, patients have experienced dilation of the fibrous anterior tissue. As a result, many other surgeons now employ a complete ring.
Complete rings can be constructed at the operating table by the surgeon or purchased as a preconstructed product under the name Medtronic/Duran Annuloplasty Ring. Still, in many cases anterior ring reinforcement is not required, and therefore partial rings are used in some patients. Partial rings can be constructed at the operating table and are also commercially available under the name Baxter/Cosgrove Annuloplasty Ring.
In some cases, the decision to use a partial or complete ring is a matter of surgeon preference. In other cases, the condition of the patient's natural valve annulus is taken into account by the surgeon upon exposure of the valve during the operative procedure. The situation results in the need for both partial and complete rings to be available to the surgeons within any given hospital. This results in added expense for the hospital, both in terms of inventory investment and storage space required to make both types of rings available. Further, the surgeon must make the choice between a partial or complete ring before the first anchoring stitches are placed into the ring.
There are several other known annuloplasty ring devices. U.S. Pat. No. 3,656,185 discloses a cardiac valvular prosthesis, e.g., for the mitral valve, consisting solely of an annular or part-annular member adapted to fit against the base of the cusps of a human heart valve and suture means for securing the member in place. The prosthesis cooperates with the natural valve cusps of the patient to form the valve. This device is a semi-rigid ring with a shape that matches the correct anatomical shape of the native valve, allowing remodeling of the valve.
U.S. Pat. No. 4,042,979 discloses an adjustable valvuloplasty ring that comprises a C-shaped frame that is sized and shaped to extend about the circumference of the left atrioventricular orifice along the base of the anterior cusp of the mitral valve; an expandable sleeve connected to the frame that together therewith forms a closed annulus, the sleeve being adapted to extend about the remainder of the circumference of the orifice; and a drawstring running through the sleeve by which the sleeve may be contracted to constrict and remodel the orifice and secured in place to maintain such constriction. This ring is entirely flexible.
U.S. Pat. No. 4,290,151 discloses an adjustable annular prosthesis for use in the surgical correction of atrioventricular orifice defects. This ring allows adjustment of the two sides of the ring independently, rather than just allowing the reduction of the ring.
U.S. Pat. No. 4,489,446 discloses a heart valve prosthesis incorporating a dynamic stiffener element. The prosthesis is adapted for securing to the annulus of an atrioventricular valve and has the characteristic of allowing normal movement of the annulus during the cardiac cycle while providing mechanical support to the valve annulus so as to maintain the valve leaflets in proper physiological alignment. The stiffener element has a plurality of reciprocating members allowing it to be modifiable in shape so as to be capable of assuming the optimum shape for a particular heart valve. This ring is an adjustable semi-rigid ring.
In U.S. Pat. No. 5,061,277, a support for a natural heart valve is disclosed. The support is generally ring shaped and has a size and shape to fit against the natural heart valve annulus. A posterior length of the support is flexible, and an anterior length of the support is semi-rigid. Accordingly, when the support is implanted, the support can shape the heart valve annulus and the first length of the support allows contraction of the heart valve annulus therealong.
U.S. Pat. No. 5,104,407 discloses an annuloplasty ring prosthesis which is formed from a selectively flexible body element having at least one defined length about its circumference which is substantially rigid. The remainder of the body element gradually increases in flexibility. The body element is a substantially annular shaped body element which is designed to be sutured to the annulus of a heart valve. The body element is formed from a non-corrosive, anti-magnetic material, and is wrapped in a material through which sutures can be drawn to suture the prosthesis to the heart valve annulus. This ring includes an out-of-plane portion on the anterior side.
U.S. Pat. No. 5,306,296 discloses adjustable and flexible atrioventricular annuloplasty rings containing circumferential radiopaque markers with mitral and tricuspid valve variations. A variant of the ring for use in the mitral region incorporates a curved framework in the anterior segment. The framework member is to maintain the intratrigonal and anterior leaflet distance during implantation. It is curved to prevent aortic outflow tract obstruction. Two or more pairs of drawstrings allow adjustment of four segments of the posterior portion of the mitral valve annulus. The variant of the ring for use in the tricuspid region incorporates a single drawstring to allow adjustment of the posterior left and right segment of the ring at implantation. The flexible contractile body of the ring common to both variants is of a biocompatible cloth. This ring includes a semi-rigid anterior region and a flexible posterior portion. The size of the ring is adjustable on both sides of the annulus.
U.S. Pat. No. 5,593,424 discloses implanting a series of devices which reduce the circumference of a diseased cardiac valve annulus or vascular structure to the desired size. Specifically, disclosed is a method and apparatus that maintains the normal shape of a vessel or induces the vessel to regain its normal shape. This facilitates localized reduction of the annulus without the use of a ring or a partial ring.
U.S. Pat. No. 5,716,397 discloses a fully flexible annuloplasty ring which is temporarily stiffened during implantation by inserting a withdrawable stiffening wire into a lumen of the ring. The annuloplasty ring has a lumen which is able to hold the stiffener prior to and during insertion. The stiffener includes a portion extending out of the lumen which can be pulled to withdraw the stiffener once the implant has been implanted. Thus, this ring has a removable rigid element allowing the ring to be rigid at the time of implantation to facilitate suture placement and remodeling of the annulus.
Therefore, what is needed is an annuloplasty ring which would allow the surgeon to anchor the posterior portion of the ring and test the annulus as part of the decision process regarding the need for a complete or partial ring. If it is decided that the anterior portion of the ring is not needed, the surgeon may then elect to separate the anterior portion of the ring from the posterior portion.